Spatially Variant Error Elimination for High-Resolution UAV SAR with Extremely Small Incident Angle

Author:

Zhang Xintian1,Tang Shiyang1ORCID,Ren Yi1,Han Jiahao1,Jiang Chenghao1,Zhang Juan1,Li Yinan2,Jiang Tong2,Dong Qi3

Affiliation:

1. National Key Laboratory of Radar Signal Processing, Xidian University, Xi’an 710071, China

2. China Academy of Space Technology (Xi’an), Xi’an 710100, China

3. Beijing Institute of Control and Electronics Technology, Beijing 100038, China

Abstract

Airborne synthetic aperture radar (SAR) is susceptible to atmospheric disturbance and other factors that cause the position offset error of the antenna phase center and motion error. In close-range detection scenarios, the large elevation angle may make it impossible to directly observe areas near the underlying plane, resulting in observation blind spots. In cases where the illumination elevation angle is extremely large, the influence of range variant envelope error and phase modulations becomes more serious, and traditional two-step motion compensation (MOCO) methods may fail to provide accurate imaging. In addition, conventional phase gradient autofocus (PGA) algorithms suffer from reduced performance in scenes with few strong scattering points. To address these practical challenges, we propose an improved phase-weighted estimation PGA algorithm that analyzes the motion error of UAV SAR under a large elevation angle, providing a solution for high-order range variant motion error. Based on this algorithm, we introduce a combined focusing method that applies a threshold value for selection and optimization. Unlike traditional MOCO methods, our proposed method can more accurately compensate for spatially variant motion error in the case of scenes with few strong scattering points, indicating its wider applicability. The effectiveness of our proposed approach is verified by simulation and real data experimental results.

Funder

National Natural Science Foundation of China

Natural Science Basis Research Plan in Shaanxi Province of China

Fundamental Research Funds for the Central Universities

Publisher

MDPI AG

Subject

General Earth and Planetary Sciences

Reference38 articles.

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